FDA approves IL-17A antagonist for treating psoriatic arthritis

The interleukin-17A antagonist ixekizumab has been approved by the Food and Drug Administration for treating adults with active psoriatic arthritis (PsA), based on two phase 3 studies, the manufacturer announced in a written statement Dec. 1.

The Eli Lilly statement noted that the approval is based on two randomized, double-blind, placebo-controlled studies; one compared ixekizumab to placebo in patients with active PsA never treated with a biologic (SPIRIT-P1) and another tested the drug in those who had been treated with a tumor necrosis factor inhibitor (TNFi) previously (SPIRIT-P2).

In SPIRIT-P1, 58% of those treated with ixekizumab 80 mg every 4 weeks had achieved a 20% reduction in a composite measure of disease activity as defined by the American College of Rheumatology (ACR20 response) at 24 weeks, compared with 30% among those on placebo. In SPIRIT-P2, 53% of those treated with ixekizumab reached that endpoint at 24 weeks, compared with 20% of those on placebo.

Ixekizumab, marketed as Taltz by Eli Lilly, was first approved by the FDA in 2016 for treating adults with moderate to severe plaque psoriasis who are candidates for systemic therapy or phototherapy.

The statement did not provide information on dermatologic endpoints, but treatment with ixekizumab “resulted in an improvement in psoriatic skin lesions in patients with PsA,” as well as “in dactylitis and enthesitis in patients with pre-existing dactylitis or enthesitis,” according to the prescribing information.

The recommended dose for patients with psoriatic arthritis is 160 mg by subcutaneous injection (two 80 mg injections) at baseline, followed by 80 mg every 4 weeks. When patients with psoriatic arthritis also have moderate-to-severe plaque psoriasis, then the prescribing information recommends following the dosing for psoriasis, which is 160 mg (two 80 mg injections) at baseline, followed by 80 mg at weeks 2, 4, 6, 8, 10, and 12, then 80 mg every 4 weeks.

The most common adverse reactions associated with ixekizumab are injection site reactions, upper respiratory tract infections, nausea, and tinea infections, according to the warnings and precautions section of the drug’s prescribing information, which lists the potential for serious infections, tuberculosis, and serious allergic reactions. Prescriptions come with a Medication Guide for patients.